S. D. Collier

Effect of ambient temperature and light intensity on physiological reactions of heavy broiler chickens

The effects of ambient temperature, light intensity, and their interaction on blood acid-base balance, metabolites, and electrolytes in broiler chickens under environmentally controlled conditions were examined in 2 trials. The experiment consisted of a factorial arrangement of treatments in a randomized complete block design. The 9 treatments consisted of 3 levels of temperatures (low = 15.6°C; moderate = 21.1°C; high = 26.7°C) from 21 to 56 d of age and 3 levels of light intensities (0.5, 3.0, 20 lx) from 8 to 56 d of age at 50% RH. A total of 540 Ross 708 chicks were randomly distributed into 9 environmentally controlled chambers (30 male and 30 female chicks/chamber) at 1 d of age. Feed and water were provided ad libitum. Venous blood samples were collected on d 21 (baseline), 28, 42, and 56. High ambient temperature significantly (P ≤ 0.05) reduced BW, partial pressure of CO(2), bicarbonate, hematocrit, hemoglobin, K(+), and Na(+) along with significantly (P ≤ 0.05) elevated pH level, Cl(-), glucose, osmolality, and anion gap concentrations. Partial pressure of O(2) was slightly increased in response to increased ambient temperature. There was no effect of light intensity on most of the blood variables examined. Acid-base regulation during high ambient temperature and light intensity exposure did not deteriorate despite a lower partial pressure of CO(2), which consequently increased blood pH because of a compensatory decrease in HCO(3)(-) concentration. Plasma corticosterone was not affected by temperature, light intensity, or their interaction. These results indicate that continuous exposure of broiler chickens to varying light intensities had a minor effect on physiological blood variables, whereas high ambient temperature markedly affected various blood variables without inducing stress in broilers.

Interactive Effects of Ammonia and Light Intensity on Hematochemical Variables in Broiler Chickens

This study examined the influence of early atmospheric ammonia exposure, light intensity throughout rearing, and their interaction on blood gases, electrolytes, and acid-base balance in broiler chickens under environmentally controlled conditions. The experiment consisted of a 3 x 3 factorial arranged in a randomized complete block design, with trials being replicated over time. The 9 treatments consisted of 3 levels (0, 25, and 50 ppm) of ammonia concentrations for 14 d and levels (0.2, 2.0, and 20 lx) of light intensities from 8 to 36 d of age. Venous blood samples were collected on d 6, 11, 14, and 35. On d 6, partial pressure of CO2 and Na+ increased significantly (P <or= 0.05), whereas partial pressure of O(2), pH, and K+ decreased with increasing ammonia concentration. As light intensity increased, pO2 and K+ were significantly (P <or= 0.05) reduced. Ammonia x light intensity interactions were observed for hemoglobin, hematocrit, K+, and BW. The interaction of ammonia and light intensity for 7 d further exacerbated physiological variables. The main effect of ammonia was more pronounced than that of light intensity. These conditions worsened as the duration of ammonia concentration exposure and light intensity increased from d 7 to 14 of exposure. However, all affected variables returned to near normal at later time points in the exposed chickens so that the apparent effects were lost. Plasma corticosterone and glucose concentrations were not significantly altered by exposure to differing levels of ammonia or light intensity, suggesting an absence of stress related to ammonia, light intensity, or their interaction. It was concluded that exposure of broiler chickens to aerial ammonia concentrations of 0 to 50 ppm from d 1 to 14 posthatch in the presence of light intensities ranging from 0.2 to 20 lx had no direct effect on some physiological blood variables and did not induce stress in broilers.

The Effects of 6/85 Live Mycoplasma gallisepticum Vaccine in Commercial Layer Hens over a 43-Week Laying Cycle on Egg Production, Selected Egg Quality Parameters, and Egg Size Distribution When Challenged Before Beginning of Lay

SUMMARY. In each of two trials, 80 commercial leghorn-type pullets were separated into two treatments with four replicates of 10 chickens in each treatment. Forty pullets were designated as controls and received no inoculation, whereas the remaining 40 pullets received the 6/85 vaccine strain of Mycoplasma gallisepticum (MG) at 10 wk of age. Hen-day egg production, egg weight, eggshell strength, Haugh unit score, pimpling incidence, and blood/meat spot incidence were monitored and recorded weekly in each trial through an entire laying cycle of 43 wk. Further, eggs from all treatments were collected daily, Monday–Thursday, and individually weighed. No significant difference was observed between the treatments for 43-wk means for hen-day egg production, for any of the monitored egg or eggshell quality parameters, or for the number of extra large, large, medium, small, pee wee, or undergrade egg sizes. A significant (P ≤ 0.05) difference was observed for the number of jumbo-sized eggs between the two treatments. Results of this study suggest that vaccination of commercial layer chickens at 10 wk of age with 6/85 strain MG does not detrimentally impact egg production, egg size distribution, or ovary/oviduct function as evidenced by selected egg parameters monitored in this study.

Effects of Increased Dosages of the Mycoplasma Gallisepticum Vaccine MYCOVAC-L® in Layer Chickens Subsequently Challenged with Virulent M. gallisepticum: Egg Production and Serologic Response

Abstract Ten-week-old Hy-Line Commercial W-36 pullets were spray-vaccinated with MYCOVAC-L® at the manufacturers recommended dosage (1×) or at 15 times that rate (15×). At 22 or 45 wk of age, subsets of 1×- and 15×-vaccinated pullets were challenged with the virulent Mycoplasma gallisepticum (MG) strain Rlow. Percent hen-day egg production was determined through week 55. Analyses for treatment effects on overall (22–56 wk) percent hen-day egg production revealed no significant differences between nonchallenged 1× and nonchallenged 15× MYCOVAC-L® treatments. Among 1× MYCOVAC-L®–vaccinated groups, Rlow challenge at 45 wk corresponded to significantly (P ≤ 0.01) lower overall egg production compared with the unchallenged 1×-vaccinated control (70.88% vs. 79.15%, respectively). Conversely, at the 15× MYCOVAC-L® dosage level, overall egg production was not significantly affected by virulent MG challenge at 45 wk compared with its unchallenged counterpart (84.09% vs. 81.03%, respectively) and could indicate increased protection from virulent MG challenge. Serologic monitoring indicated the virulent MG challenge was consistently (100%) associated with seroconversion. Comparisons among the nonchallenged experimental treatments indicated that vaccinations at the 15× MYCOVAC-L® dosage rate were associated with a greater seroconversion rate at weeks 21, 27, and 44, but not at week 50.

A Comparative Study of Live Attenuated F Strain–Derived Mycoplasma gallisepticum Vaccines

SUMMARY. Commercially available attenuated strains of Mycoplasma gallisepticum (MG) are commonly used within the layer industry to control MG-induced mycoplasmosis. Among these are two live MG vaccines derived from the moderately pathogenic MG “chick F” strain. In the present study, the commercially available F strain derivatives were compared for their ability to elicit seroconversion, persist in vivo, and protect against virulent MG-induced airsacculitis. In addition, a noncommercial laboratory–derived high-passage F strain isolate was included in the study. Commercial (Hy-Line W-36) layers were placed in biological isolation units at 9 wk of age (woa). At 10 woa, birds within each biological isolation unit were treated via eye-drop application with one of the three F strain–derived vaccines at one of four levels (1×, 10−1×, 10−2×, or 10−3×). For the commercially available F strain derivatives, 1× equaled the manufacturers recommended dose. The 1× dose of the noncommercial laboratory–maintained F strain derivative equaled 20 µl of a 48 hr culture. For wk 1–6 postvaccination (p.v.), sera were collected weekly from each bird, and seroconversion was assessed via serum plate agglutination (SPA). Virulent MG (strain Rlow) challenge occurred via intratracheal inoculation at 7 wk p.v. Necropsies were subsequently performed to assess challenge-associated airsacculitus. For each F strain derivative applied at 1× and 10−1×, 100% seroconversion, as measured by SPA, was demonstrated by 6 wk p.v., and rates at the 10−2× dosage were 10% and 90% for the commercial vaccines and 60% for the laboratory-derived strain in this period. Following challenge, airsacculitis was observed in 66.67% of the nontreated controls but not in any 1×- or 10−1×-treated bird independent of applied F strain derivative. RESUMEN. Estudio comparativo de vacunas vivas atenuadas derivadas de la cepa F de Mycoplasma gallisepticum. Cepas atenuadas de Mycoplasma gallisepticum disponibles en el mercado se utilizan comúnmente en la industria de gallinas de postura para controlar la micoplasmosis inducida por M. gallisepticum. Entre ellas se encuentran dos vacunas vivas de M. gallisepticum derivadas de la cepa moderadamente patógena “chick F” de M. gallisepticum. En el presente estudio, las cepas derivadas de la cepa F disponibles en el mercado se compararon por su capacidad para estimular la seroconversión, por su persistencia in vivo, y en la protección conferida contra la aerosaculitis inducida por M. gallisepticum virulento. Además, una cepa F no comercial de laboratorio y derivada de un aislamiento con alto pasaje se incluyó en el este estudio. Aves de postura comerciales (Hy-Line W-36) fueron colocados en unidades de aislamiento biológico a las 9 semanas de edad. A las diez semanas de edad, las aves dentro de cada unidad de aislamiento biológico fueron inoculadas a través de la aplicación de gotas oculares con una de las tres vacunas derivadas de la cepa F en uno de los cuatro niveles (1×, 10−1×, 10−2×, ó 10−3×). Para los derivados de la cepa F disponibles en el mercado, 1x fue igual a la dosis recomendada por el fabricante. La dosis 1x de la cepa F de laboratorio no comercial fue igual a 20 µl de un cultivo de 48 horas. Durante seis semanas después de la vacunación, los sueros fueron recolectados semanalmente de cada ave, y se evaluó la seroconversión a partir de las muestras de suero a través de aglutinación en placa. Se realizó un desafío virulento (cepa Rlow) a través de la inoculación intratraqueal a las 7 semanas después de la vacunación. Se realizaron posteriormente necropsias para evaluar la aerosaculitis asociada con el desafío. Para cada derivado de la cepa F aplicada en los niveles 1× y 10−1×, se observó 100% de seroconversión determinada por la aglutinación en placa por seis semanas y el nivel de dosis 10-2 mostraron porcentajes de seroconversión de 10% y 90% para las vacunas comerciales y de 60% para la cepa derivada de laboratorio para este período. Después de desafío, se observó aerosaculitis en el 66.67% de los controles no tratados, pero no se observó en ninguna de las aves tratadas con los niveles 1× ó 10−1×, independiente del derivado de la cepa F aplicado.

A Self-Propelled, Constant-Speed Spray Vaccinator for Commercial Layer Chickens

Abstract Vaccination of commercial layer chickens is labor intensive and often results in poor rates of seroconversion, which, in turn, generally correlate with decreased flock uniformity and performance. Attempts to improve the vaccination process include numerous variations of individual shop-built vaccinators in use by the layer sector of the poultry industry. Each of these vaccinators has limitations that contribute to poor vaccinations. Major problems include the nonuniform speed of the applicator system and pressure fluctuations at the spray nozzles, which contribute to sporadic dispersion of the vaccine as the vaccinator is pushed or carried past the cages. A battery-powered, self-propelled, constant-speed vaccinator was designed and constructed that operates with constant nozzle pressure. In field use, this vaccinator has resulted in both labor savings (reduction of manpower from five to one to vaccinate 75,000 chickens) and time savings (from 45 min to 7.5 min/poultry house) as well as improved vaccination results (higher positive seroconversion rates) against the poultry pathogen Mycoplasma gallisepticum (MG), a bacterium associated with losses of 15.7 eggs/hen over a 45-wk laying period in MG-infected layers as compared with layers maintained free from infection with MG.

Effects of light sources and intensity on broilers grown to heavy weights. Part 1: Growth performance, carcass characteristics, and welfare indices

This study investigated the effects of light sources and light intensity on growth performance, carcass characteristics, and welfare indices of heavy broilers (>3.0 kg) in 4 trials with 2 replications per trial. A total of 960 one-day-old Ross×Ross 708 chicks (30 males/30 females/room) were randomly distributed into 16 environmentally controlled rooms at 50% RH. A 4×2 factorial treatment structure evaluated 4 light sources (incandescent [ICD, standard], compact fluorescent [CFL], neutral light emitting diode [Neutral-LED], and cool poultry specific filtered LED [Cool-PSF-LED]) and 2 levels (5 lx, 20 lx) of light intensities. Each of the 4 light sources was paired with one of the 2 light intensities. Birds were fed the same diet with a 4-phase feeding program (starter, grower, finisher, and withdrawal). Feed and water were provided ad libitum. Birds and feed were weighed on one, 14, 21, 28, 42, and 56 d of age for growth performance. All mortality was recorded daily and feed conversion was adjusted for mortality. Immune response was determined on d 28 to d 35, whereas other welfare indices were performed on d 42 and 49, respectively. At d 56 of each trial, 20 (10 males and 10 females) birds from each room were processed to determine weights and yields. The BW, BW gain, live weight, and carcass weights of birds reared under Cool-PSF-LED were different (P≤0.05) in comparison to birds reared under ICD. However, FI, FCR, and mortality were not affected by treatments. There was no effect of treatments on fat or breast and tender weights and yields. In addition, there was no effect of treatments on ocular development, immune response, and other welfare indices, suggesting that the light sources evaluated did not compromise welfare of heavy broilers. It was concluded that the 3 light sources evaluated in this study may be suitable for replacement of ICD light source in poultry facilities to reduce energy cost and optimize production efficiency.

Effects of Time-Specific F-Strain Mycoplasma gallisepticum Inoculation Overlays on Prelay ts11-Strain Mycoplasma gallisepticum Inoculation on Performance Characteristics of Commercial Laying Hens

Mycoplasma bacteria are virtually ubiquitous in layer chicken flocks, and Mycoplasma gallisepticum is the species of greatest concern to commercial egg producers. Live M. gallisepticum vaccines were initially approved by the USDA for use in commercial layers in 1988 to help control M. gallisepticum outbreaks. In the present study, 2 trials were conducted to determine the effects of 2 currently available live Mycoplasma vaccines (the ts11-and F-strains) when used together. The following 4 inoculation treatments were used: 1) sham inoculation at 10 wk of age, 2) ts11 at 10 wk, 3) ts11 at 10 wk overlaid by the F-strain at 22 wk, and 4) ts11 at 10 wk overlaid by the F-strain at 45 wk. In each trial, at various ages between 18 and 57 wk of age, hen mortality; BW; egg weight; egg production; eggshell breaking strength; incidences of egg blood spots, egg meat spots, and eggshell pimpling; and eggshell weight per unit of surface area were assessed. The effects of inoculation treatment on egg weight at 27, 37, and 38 wk were inconsistent and variable. Eggshell pimpling and egg blood spot incidences at 56 wk were highest in eggs belonging to the ts11 at 10 wk/F-strain at 45 wk group. Despite increases in pimpling and blood spot incidences very late in production because of the ts11 at 10 wk/F-strain at 45 wk treatment, performance in layers was not adversely affected by a 10-wk ts11 inoculation alone or in conjunction with subsequent overlay inoculations of the F-strain during lay. It is therefore suggested that the 10-wk inoculation of commercial layers with ts11 may reduce the negative impacts of a prelay F-strain inoculation on performance, as reported in earlier studies, while providing protection against subsequent field strain M. gallisepticum infections. Furthermore, the ts11- and F-strain M. gallisepticum treatment combinations may overcome some of the inadequacies that prelay ts11- or F-strain M. gallisepticum vaccines may have when given independently.

The Effects of Increasing Sodium Chloride Concentration on Mycoplasma gallisepticum Vaccine Survival in Solution

Abstract Lyophilized Mycoplasma gallisepticum (MG) vaccines are generally rehydrated and diluted with distilled or chlorine-free water as per manufacturer recommendations. However, as mycoplasma species lack a cell wall, this can lead to decreased viability of live vaccine during administration. The ability of phosphate-buffered saline (PBS) to prevent losses in live vaccine viability was examined. It was shown that a concentration of 1× PBS prevented the two–fourfold decrease in MG viability seen when the vaccines were diluted with water alone.

Interactive effects of photoperiod and light intensity on blood physiological and biochemical reactions of broilers grown to heavy weights

The effects of photoperiod, light intensity, and their interaction on blood acid-base balance, metabolites, and electrolytes in broiler chickens under environmentally controlled conditions were examined in 2 trials. A 3 × 3 factorial experiment in a randomized complete block design was used in this study. In each trial, all treatment groups were provided 23L:1D with 20 lx of intensity from placement to 7 d, and then subjected to the treatments. The 9 treatments consisted of 3 photoperiods [long/continuous (23L:1D) from d 8 to 56, regular/intermittent (2L:2D), and short/nonintermittent (8L:16D) from d 8 to 48 and 23L:1D from d 49 to 56, respectively] and exposure to 3 light intensities (10, 5.0, and 0.5 lx) from d 8 through d 56 at 50% RH. Feed and water were provided ad libitum. Venous blood samples were collected on d 7, 14, 28, 42, and 56. Main effects indicated that short/nonintermittent photoperiod significantly (P < 0.05) reduced BW, pH, partial pressure of O2, saturated O2, Na(+), K(+), Ca(2+), Cl(-), osmolality, triiodothyronine (T3), and total protein along with significantly (P < 0.05) elevated partial pressure of CO2, hematocrit, hemoglobin, and lactate concentrations. In addition, there were no effects of photoperiod on HCO3(-), glucose, anion gap, and thyroxine (T4). Plasma corticosterone was not affected by photoperiod, light intensity, or their interaction. There was no effect of light intensity on most of the blood variables examined. Acid-base regulation during photoperiod and light intensity exposure did not deteriorate despite a lower pH and higher partial pressure of CO2 with normal HCO3(-). These results indicate that continuous exposure of broiler chickens to varying light intensities had a minor effect on blood physiological variables, whereas the short photoperiod markedly affected most blood physiological variables without inducing physiological stress in broilers.